Climate change may reduce biodiversity leading to a reduction in ecosystem productivity. Despite numerous reports of a strong correlation of microbial diversity and ecosystem productivity, little is known about warming effects on plant associated prokaryotes. Here we explore the impact of experimental warming on the microbial and nitrogen-fixing (diazotroph) community associated with the widespread and ecologically relevant Sphagnum (peat moss) in a field warming experiment. To quantify changes in the abundance, diversity, and community composition of Sphagnum microbiomes with warming we utilized qPCR and Illumina sequencing of the SSU rRNA and nifH gene. Additionally we measured functional changes by assaying nitrogenase activity with an acetylene reduction assay and 15N2 labeling.
Results/Conclusions
We found microbial and diazotroph community richness and diversity decreased with warming (p<0.05). The diazotroph communities shifted from diverse communities to domination by primarily Nostocaceae (25% in control samples to 99% in elevated temperature samples). In addition, nitrogen fixation activity measured with the acetylene reduction assay (ARA) decreased with heating treatment. This suggests the negative correlation of temperature and microbial diversity corresponds to a reduction in functional potential within the diazotroph community. The results indicate that climate warming may alter the community structure and function in peat moss microbiomes, with implications for impacts to host fitness